PR: cockroachdb/cockroach#45609

From release notes:

CockroachDB now supports accessing the Nth column in a column with tuple type using the syntax (...).@N, for example: SELECT (t).@2 FROM (SELECT (1,'b',2.3) AS t). This is a CockroachDB-specific extension. [#45609][#45609] {% comment %}doc{% endcomment %}

CockroachDB now supports expanding all columns of a tuple using the .* notation, for example: SELECT (t).* FROM (SELECT (1,'b',2.3) AS t). This is a CockroachDB-specific extension. [#45609][#45609] {% comment %}doc{% endcomment %}